Clutch release mechanism with a device for compensating for lack of precision in a friction clutch of a motor vehicle

ABSTRACT

A clutch-release mechanism for actuating the friction clutch of a motor vehicle, installed concentrically around a guide sleeve, includes a release bearing with an inner ring and an outer ring as well as a sliding sleeve. The inner ring is in working contact with a release spring of the friction clutch and the outer ring is in working contact with the sliding sleeve by way of a sliding surface, and the release mechanism has both a first device for compensating for a tilt of the center axis of the friction clutch with respect to the center axis of the guide sleeve and/or for a wobbling eccentricity of the release spring, and a second device for compensating for an offset between the above-mentioned center axes. The first device consists of a modified raceway for the balls, where the race has both a first race radius and a second race radius to form a surface in the form of a spherical segment, where differences between the angles of the release spring and of the release bearing are compensated. Because the raceway can be produced in any case with high precision in the outer ring and because the rolling contact of the parts is lubricated with grease and protected from the outside environment by seals, no additional components are required for the release mechanism, and there are no additional friction points to be lubricated and sealed.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to a clutch release mechanism for actuatinga friction clutch between an internal combustion engine and atransmission of a motor vehicle. This mechanism is installed asconcentric assembly around a guide sleeve mounted on a transmissionshaft, comprising a release bearing with an inner ring and an outer ringas well as a sliding sleeve, where one of the rings, preferably theinner ring, is in working connection with a release spring of thefriction clutch and the outer ring is in working connection with thesliding sleeve. The assembled release mechanism has a first device forcompensating for a tilt of the center axis of the friction clutch withrespect to the center axis of the guide sleeve and/or for a wobblingeccentricity of the release spring and a second device for compensatingfor an offset between the previously mentioned center axes.

[0003] 2. Description of the Related Art

[0004] DE 199 12 431 A1 (equivalent to UK patent application GB 2 339000) discloses a clutch release mechanism for a friction clutch of amotor vehicle. This mechanism includes a release bearing, which ismounted on a sliding sleeve, and a disk spring, which belongs to thefriction clutch and is in working connection with the release bearing.Particularly, the disclosed mechanism includes two areas withcomplementary surfaces in the form of segments of a sphere which areprovided between the disk spring and the release bearing. The two areaswith the surfaces in the form of spherical segments are provideddirectly or indirectly on the disk spring, and the areas forming thesurfaces in the form of spherical segments can be shifted radiallytoward the release bearing.

[0005] The areas connected in this way by surfaces in the form sphericalsegments are slide on each other and are formed from in part by thetongues or a compensating ring which is mounted between the disk springand a flange part provided to serve as the pressure plate of the releasebearing. In addition, the spherical surfaces on the rings are producedprimarily by a grinding process, which increases costs related to boththe production and the material of the rings.

SUMMARY OF THE INVENTION

[0006] As the first device for compensating for a tilt of the centeraxis of the friction clutch with respect to the center axis of the guidesleeve and/or for a wobbling eccentricity of the release spring, theproposed clutch-release mechanism according to the invention has amodified race for the balls of the release bearing, preferably in theouter ring. As is known in the art, this race includes a first raceradius, which, as the osculation radius, is only slightly larger thanthe radius of the balls. According to the present invention, this raceradius is interrupted by a second race radius, which is much larger thanthe osculation radius and has its starting point on the center axis ofthe guide sleeve. It can be concluded from the fact that the second raceradius has its starting point on the center axis of the guide sleevethat the ring-shaped surface formed by the second race radius is asurface in the form of a spherical segment, which, in functional terms,represents a ball joint for the inner ring. As an angular-contact ballbearing with the ability to oscillate, the inner ring of the releasebearing can therefore react to an eccentric wobbling of the releasespring by following the imprecise course of the rotating tongues duringwhich process the balls in the spherically shaped surface of the firstrace radius do not roll in a plane perpendicular to the center axis ofthe guide sleeve but rather along a track which is at an angle to thisplane. This track, which oscillates from one side to another, candeflect only as far as a specific maximum deflection angle, where thewidth of the surface in the shape of a spherical segment is determinedby the adjacent halves of the first race radius. The force exerted bythe balls on the spherical surface depends on the position of the secondrace radius, where the resulting bearing pressure angle decreases as thestarting point of the second race radius moves closer to the releasebearing.

[0007] According to the present invention, a second device has a slidingsurface between the release bearing and the sliding sleeve in a planeperpendicular to the center axis of the guide sleeve to compensate foran offset between the center axis of the friction clutch and the centeraxis of the guide sleeve. The release bearing can be pushed along thissliding surface with respect to the sliding sleeve within certain limitsand, thus, can be moved out of its coaxial position with respect to theguide sleeve. The two devices can be combined in one release mechanism,it being advisable in this case for the release bearing to accompany themovements of the clutch spring by virtue of the contact of the rotatinginner ring of the bearing with the tongues of the clutch spring, forwhich reason the two devices must be installed between the releasebearing and the guide sleeve.

[0008] The sliding surface of the release mechanism described above islocated on the outer ring of the release bearing in a planeperpendicular to the center axis of the guide sleeve, where, withincertain limits, the release bearing can be pushed along the sliding ofthe sliding sleeve and thus moved out of a position coaxial with respectto the guide sleeve. Because the release bearing and the sliding sleeveare connected elastically together by a clamp, static friction iscreated, which stabilizes the release bearing when it has movedoff-center. A ring-shaped stop is provided on the sliding surface of thesliding sleeve. The outer ring can make contact with this stop, whichlimits the extent to which the outer ring can be deflected from itscentered position.

[0009] It is an object of the present invention to provide aclutch-release mechanism for actuating the release spring of a frictionclutch of a motor vehicle which has a device for compensating for a tiltof the center axis of the friction clutch with respect to the centeraxis of a guide sleeve and/or for compensating for an offset of theabove-mentioned center axes and/or for a wobbling eccentricity of therelease spring. Preferably, such a mechanism occupies a minimal amountof space and has a minimal cost.

[0010] Other objects and features of the present invention will becomeapparent from the following detailed description considered inconjunction with the accompanying drawings. It is to be understood,however, that the drawings are designed solely for purposes ofillustration and not as a definition of the limits of the invention, forwhich reference should be made to the appended claims. It should befurther understood that the drawings are not necessarily drawn to scaleand that, unless otherwise indicated, they are merely intended toconceptually illustrate the structures and procedures described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a cross-sectional view of a clutch-release mechanismwith a sliding sleeve and a release bearing with an outer ring and aninner ring, the mechanism also including a common slide face between theouter ring and the sliding sleeve in a phase perpendicular to the centeraxis of the sliding sleeve; and

[0012]FIG. 2 is a partial cross-sectional view of the outer ring with arace consisting of several segments.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

[0013]FIG. 1 shows a clutch-release mechanism 50 for actuating afriction clutch using a release spring 5. The release mechanism 50 has arelease bearing 1, which is a ball bearing with an inner ring 3, balls8, and an outer ring 6. The inner ring 3 rests by a contact surface 4against the tongues of the release spring 5. The outer ring 6 has asliding surface 7 indirectly or directly in common with a sliding sleeve2 in a plane 14 transverse to the center axis of the release bearing 1.The sliding sleeve has a ring-shaped stop 15 for the outer ring 6 of therelease bearing 1. A clamp 16 connects the release bearing 1 to thesliding sleeve 2 to form a structural unit.

[0014] In FIG. 2, the outer ring 6 has a race 9 which includes aring-shaped surface with a first race radius 10, an intermediatering-shaped surface with a second race radius 11, and an innerring-shaped surface, again with the first race radius 10. As the balls 8rotate in the outer ring 6, they can move within a deflection angle 13.They are guided in a conventional race in the inner ring 3.

[0015] The advantage of the first device consists in that only the race9 for the balls 8 must be modified, preferably in the outer ring 6, inthat a second race radius 11 is machined into the ring next to a firstrace radius 10 to form a surface in the form of a spherical segment,where differences between the angle of the release spring 5 and theangle of the release bearing 1 can thus be compensated. Because the race9 can be in any case produced in the outer ring 6 with high precisionand because the rolling contact between the parts is lubricated withgrease and protected by seals from the outside environment, noadditional components are required for the release mechanism, and noadditional friction points are present which must be lubricated andsealed.

[0016] Thus, while there have shown and described and pointed outfundamental novel features of the invention as applied to a preferredembodiment thereof, it will be understood that various omissions andsubstitutions and changes in the form and details of the devicesillustrated, and in their operation, may be made by those skilled in theart without departing from the spirit of the invention. For example, itis expressly intended that all combinations of those elements and/ormethod steps which perform substantially the same function insubstantially the same way to achieve the same results are within thescope of the invention. Moreover, it should be recognized thatstructures and/or elements and/or method steps shown and/or described inconnection with any disclosed form or embodiment of the invention may beincorporated in any other disclosed or described or suggested form orembodiment as a general matter of design choice. It is the intention,therefore, to be limited only as indicated by the scope of the claimsappended hereto.

What is claimed is:
 1. A clutch-release mechanism for actuating afriction clutch disposed between an internal combustion engine and atransmission of a motor vehicle and concentrically around a guide sleevemounted on a transmission shaft, comprising a clutch-release bearingincluding an inner ring, balls, an outer ring and a sliding sleeve; oneof said rings being in working connection with one of a release springof the friction clutch and said sliding sleeve; said clutch-releasemechanism further comprising a first device for compensating for one ofa tilt of a center axis of the friction clutch with respect to a centeraxis of the guide sleeve and a wobbling eccentricity of a release springand a second device for compensating for an offset between said centeraxes; said first device comprising a race (9) for the balls (8) having afirst race radius (10) and a second race radius (11).
 2. Theclutch-release mechanism according to claim 1, wherein said first raceradius (10) having, relative to said balls, a conventional osculation ofan angular-contact ball bearing and said second race radius (11) havinga smaller osculation for said balls (8) relative to said first raceradius.
 3. The clutch-release mechanism according to claim 1, whereinsaid first race radius (10) is interrupted by said second race radius(11) and the starting point of said second race radius (11) being on thecenter axis of the guide sleeve.
 4. The clutch-release mechanismaccording to claim 1, wherein said race (9) is disposed in one of saidinner ring (3) and said outer ring (6).
 5. The clutch-release mechanismaccording to claims 1, wherein said race (9) is disposed in said outerring and has the form of the surface of a spherical segment along saidsecond race radius (11), said surface having a width determined by adeflection angle (13) around which said inner ring (3) can oscillate. 6.A clutch-release mechanism for actuating a friction clutch disposedbetween an internal combustion engine and a transmission of a motorvehicle and concentrically around a guide sleeve mounted on atransmission shaft, comprising a clutch-release bearing including aninner ring, balls, an outer ring and a sliding sleeve; one of said ringsbeing in working connection with one of a release spring of the frictionclutch and said sliding sleeve; said clutch-release mechanism furthercomprising a first device for compensating for one of a tilt of a centeraxis of the friction clutch with respect to a center axis of the guidesleeve and a wobbling eccentricity of a release spring and a seconddevice for compensating for an offset between the center axis of thefriction clutch and the center axis of the guide sleeve, said seconddevice comprising a slide face (7) between the release bearing (1) andthe sliding sleeve (2) in a plane (14) perpendicular to the center axisof the guide sleeve, and wherein the release bearing (1) can be pushedalong said slide face (7) with respect to the sliding sleeve (2) andmove out of a coaxial position with respect to the guide sleeve.
 7. Theclutch-release mechanism according to claim 6, wherein said slide face(7) of said sliding sleeve (2) cooperates directly or indirectly withsaid slide face (7) on said outer ring (6).
 8. The clutch-releasemechanism according to claim 1, wherein said first device and saidsecond device are both integrated into the clutch-release mechanism. 9.The clutch-release mechanism according to claim 6, wherein said releasebearing (1) is offset with respect to a center axis of said slidingsleeve (2), said offset being limited in the area of said slide face (7)by a stop (15).
 10. The clutch-release mechanism according to claim 6,wherein said first device and said second device are both integratedinto the clutch-release mechanism.